Monoclonal antibodies have been generated in our laboratory that recognize either preferentially, restricted or unique antigens expressed by prostate tumors. Two of these monoclonal antibodies, designated TURP- 27 and PD41 bind novel glycoprotein antigens. The objective of the proposed study is to further determine the nature of these unique antigens and then, using this information, develop sensitive and specific immunoassays. The long-term goal of this study is to develop immunoassays to enhance both diagnosis and prognosis of prostate cancer, the most common cancer in U.S. males. The following studies will be performed to achieve this goal. (1) The TURP-27 and PD41 target antigens will be chromatographically purified, the biochemical nature of the antigens determined, and the core proteins isolated and characterized chemically and immunologically. (2) cDNA clones for the polypeptide or core protein of the TURP-27 and PD41 antigens will be isolated and recombinant fusion proteins prepared using recombinant DNA technology. (3) Second generation monoclonal antibodies will be produced against the purified native antigens, core proteins and recombinant antigens. First and second generation antibodies will be used to map the antigenic epitopes on the TURP-27 and PD41 native, core protein and recombinant antigens. (4) Second generation antibodies having a high binding affinity for the target antigen and recognizing different antigenic epitopes will be selected for development of two-site (double determinant) immunoradiometric assays. Various combinations of first and second generation monoclonal antibodies will be evaluated to establish the most sensitive and specific assays for measuring the target antigen in body fluids. (5) Serum from age-matched normal donors and from patients with benign and malignant disease will be tested by these immunoassays to determine normal baseline prostate levels for the TURP-27 and PD41 antigens. The diagnostic and prognostic potential of the assays will then be determined, and the results compared with the present serum PSA prostate tumor marker immunoassay. The clinical evaluation of these markers will involve correlation of the serum assay results with tissue expression of the tumor markers, with tumor stage and grade, the effect of treatment on antigen expression, and the time to tumor progression and survival.